Separation of active components tyrosol and salidroside from Rhodiola rosea crude extract by two-step multistage fractionation extraction

Abstract

Rhodiola rosea contains many active ingredients, such as salidroside and tyrosol. However, separating the active components from Rhodiola rosea crude extract is difficult due to their similar physical properties. Multi-stage centrifugal fractionation extraction method was used due to its strong extraction and separation ability. Three solvents (n-butanol, n-amyl alcohol, and isobutyl acetate) with better distribution coefficient (k) and separation factor (α) were selected from nine organic solvents by single-stage extraction experiment. NaCl was used to break the two-phase emulsification during extraction. A two-step multi-stage extraction process was designed to separate multiple components. The multi-stage fractionation extraction experiments were carried out under the theoretical optimum conditions. In the first step, monomer 6 (tyrosol) was isolated and enriched in organic phase with a purity of over 94% using the above three solvents. In the second step using n-butanol as solvent, monomer 3 (picein) was enriched in organic phase with a purity of 93.6%, and monomer 5 (salidroside) was enriched in aqueous phase with a purity of 85.2%. Finally, the effect of the number of stages was simulated for the separation of picein. The yield of picein reached 80%, and the purity was close to 100% by more than 20 stages.